Electricity is a prime and constant requirement for unhindered and smoothly running operations throughout the world, and electric power is a cornerstone technology upon which public and private organizations depend. The task of supplying electrical power on a reliable basis is accomplished by electric power systems. Conventional electrical power systems have a burden of providing continuous transmission and distribution of electrical power from sources of power generation which can suddenly change their power output levels to various consumers who draw power in varying, often rapidly fluctuating amounts, from the electrical power systems to which they are connected. Electric power transmission and distribution systems are also called power grids, or simply, grids.
Demand and consumption of electrical power is ever increasing. That demand places substantial strain on power grids. Recent and continuing additions of wind- and solar-based electrical generation to the power grids has increased power delivery complexity as these sources are prone to cease or increase generation without prior notice or planning as a result of unmanageable changes in the environment such as a passing cloud. Cascading power outages can occur as a result of various fluctuations in voltage of connected power grids. Such outages (c.f., the 2005 and 2011 Southwestern U.S. and Mexico regional blackouts, the 1965, 1977, and 2003 Northeastern U.S. and Canada regional blackouts, the 2006 Franco-German blackout, and the 1999 Southern Brazil blackout) result in disruptions of government and public services, industry and private lives that cause significant economic losses and deaths.
Control of grid voltage is important for proper operation of electrical power equipment. Without proper voltage control, connected electrical equipment can be damaged or destroyed by overheating. Voltage collapse can occur as a result of an increase in load on power grids or insufficient generation of electric power. Voltage increase can occur as a result of an increase in generation or a decrease in load. Also, various natural or man-made phenomena, including electromagnetic pulses, can increase grid voltage above design levels.
Conventional Transmission and Distribution systems are designed to operate at a nominal voltage with minimum and maximum voltage limits for both abnormal and emergency operation specified and established according to safety guidelines for equipment protection. However, when power demand surges or generation is reduced, grid voltage may undesirably decrease towards or below a lower voltage limit or may undesirably increase towards or above an upper voltage limit.
Conventional systems rely on human operators or properly programmed computers to reconfigure the grid system to control fluctuations in the grid voltage. Computers is meant to describe any programmable electronic device, such as a sensor. Following the protocol of conventional systems, a grid operator must: (i) observe or be alerted to voltage changes occurring from power demand surges or generation reductions; and (ii) assess and respond by taking immediate actions to reconfigure the grid to bring voltage back within an acceptable level. The existing systems and methods for controlling reductions in transient grid voltage require action by an operator or a properly programmed and functioning computer to cause conventional electric power systems to shed some or all load connected to the system or to connect additional generation to the system. Similarly, those existing systems and methods for controlling increases in transient grid voltage require action by an operator or a properly functioning computer to add load onto the system or to reduce or disconnect generation from the system. In addition, when external electromagnetic pulses induce overvoltage, some conventional systems and methods attempt to respond by connecting a shunt once the pulse-generating event is detected to divert the pulse around vulnerable electrical components via a low-inductance, high-current-capacity shunt circuit.
Conventional systems and methods for controlling the grid voltage in response to transient undervoltage and overvoltage conditions also are not designed to take into account the substantial transient increase in electrical energy in the electric power transmission and distribution systems generally. Specifically, those conventional systems and methods do not take into account the voltages of the neutral phase that can be created in a geomagnetically-induced voltage condition.